The present invention relates to a sheet feed device installed in an electronic copier, printer or like apparatus for feeding sheets one by one to a predetermined station in the apparatus.
In the art of electronic copiers, printers, etc., there is known a sheet feed device, or sheet feeder, of the type using a sheet feed tray which includes a movable bottom plate for carrying a stack of sheets thereon, and a plurality of gears which are selectively driven by a motor to raise the sheets on the bottom plate to a predetermined sheet feed position. Specifically, as the gears rotate driven by the motor, a pivotal lever is moved to raise the bottom plate of the tray until the sheet stack on the tray reaches the sheet feed position. The tray is provided with a cover which is openable for replacement or supply of sheets.
In a prior art sheet feeder of the type described, sheets are replaced or supplied by pulling the sheet feed tray out of the housing of, for example, an electronic copier and canceling the intermesh between the gears so that the bottom plate of the tray is lowered from the sheet feed position to an initial or sheet supply position. The problem with such a sheet feeder is that when the tray is inserted again into the housing after the replacement or supply of sheets, the gears are apt be intermeshed only incompletely causing the bottom plate of the tray to fail to rise or, if successfully risen, to collapse afterward.